This way the posted var "sort" contains a json of all fields and directions instead of the name only. the modified load-function is backward compatible in case you are using another store with the old functionality.

E.g.old style:

PHP Code:

sort=street_descrdir=ASC

new style

PHP Code:

sort=[{"field":"street_descr","direction":"ASC"},{"field":"postal_zip_cd","direction":"ASC"}]dir=null //is not used anymore here

- unselect a column when it is clicked whith CTRL pressed and was already selected before
- support both menu entries in the column menu for sorting the columns
- only select one single column and unselect all others if a column is clicked which has _not_ been selected before